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NESC0486 ANCON.

ANCON, Space-Independent Reactor Kinetics with Linear or Nonlinear Thermal Feedback

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1. NAME OR DESIGNATION OF PROGRAM:  ANCON.
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2. COMPUTERS
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Program name Package id Status Status date
ANCON NESC0486/01 Tested 01-APR-1975
ANCON NESC0486/02 Tested 01-MAR-1975

Machines used:

Package ID Orig. computer Test computer
NESC0486/01 CDC 6600 CDC 6600
NESC0486/02 IBM 370 series IBM 370 series
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3. DESCRIPTION OF PROBLEM OR FUNCTION

ANCON solves the point-reactor  kinetic equations including thermal feedback. Lump-type heat balance equations are used to represent the thermodynamics, and the heat capacity of each lump can vary with temperature. Thermal feedback can be either a linear or a non-linear function of lump temperature, and the impressed reactivity can be either a polynomial or sinusoidal function.
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4. METHOD OF SOLUTION

In ANCON the system of coupled first-order differential equations is solved by a method based on continuous analytic continuation (references 2 and 3). The basic procedure consists of expanding all the dependent variables except reactivity  in Taylor series, with a truncation error criterion, over successive intervals on the time axis. Variations of the basic procedure are used to increase the efficiency of the method in special situations. Automatic switching from the basic procedure to one of its variations (and vice-versa) may occur during the course of a transient. The method yields an analytic criterion for the magnitude of the time-step at any point in the transient.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The program is currently restricted to a maximum of six delayed neutron groups and  a maximum of 56 lumps. Larger problems can be accommodated on a 65K  computer by increasing the dimensions of a few subscripted variables. Also, the code is currently restricted to a constant external transport delays, only the open-loop response of a reactor  can be computed with ANCON.
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6. TYPICAL RUNNING TIME

Running time is highly problem-dependent, depending on such factors as the number of equations in the system,  the feedback and heat balance options used, the time at which the transient is terminated, and whether the transient is slow or fast.  Most problems that have been run with ANCON required 1 to 10 minutes on the CDC 6600. NESC executed the sample problem in 30 CPU seconds  on an IBM 3033.
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7. UNUSUAL FEATURES OF THE PROGRAM

The most important characteristic  of the computational method is that it yields an analytic criterion  for the magnitude of the time-step. This criterion is such that the  time-step automatically expands or contracts, depending on the behavior of the dependent variables within each interval. The use of this criterion quarantees that the accumulated fractional error in each dependent variable is always less than N*E, where N is the number of time-steps and E is an input truncation error parameter.
Also, the code is structured in a form such that reactivity, heat balance, and source options other than those presently available can be incorporated with a minimum of code modification.
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8. RELATED AND AUXILIARY PROGRAMS

The ANCON output is printed but not plotted because plotting codes are frequently system-dependent. However, the output is saved on logical unit TAPE1, which may be either a tape unit or a disk file. From TAPE1, the user can make plots with his own plotting routines. The original IBM 360 conversion was by P. Henline of the National Energy Software Center.
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9. STATUS
Package ID Status date Status
NESC0486/01 01-APR-1975 Tested at NEADB
NESC0486/02 01-MAR-1975 Tested at NEADB
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10. REFERENCES

- J.C. Vigil,
Solution of the Nonlinear Reactor Kinetics Equations by Continuous    Analytic Continuation,
  LA-3518, May 1, 1966.
- J.C. Vigil,
  Solution of the Reactor Kinetics Equations by Analytic
  Continuation
  Nuclear Science and Engineering, Vol. 29, pp. 392-401, 1967.
NESC0486/01, included references:
- J.C. Vigil:
  ANCON - User's Manual
  LA-4616 (May 1971).
NESC0486/02, included references:
- J.C. Vigil:
  ANCON - User's Manual
  LA-4616 (May 1971).
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11. MACHINE REQUIREMENTS

ANCON requires 32K words of central memory, one peripheral storage device (logical unit 1), card reader (logical unit 10), print (logical unit 9), and card punch. Standard system- library functions and a CLOCK routine are used. The CLOCK routine is not essential. A dummy CLOCK routine is provided with the IBM 360 version package.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC0486/01 FORTRAN-IV
NESC0486/02 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  SCOPE 3.2 (CDC 6600) and OS/360 (IBM 360).
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
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15. NAME AND ESTABLISHMENT OF AUTHOR

Contributed by:
CDC 6600  John C. Vigil
          Los Alamos Scientific Laboratory
          P.O. Box 1663
          Los Alamos, New Mexico 87554

IBM 360B  E.T. Dugan
          Department of Nuclear Engineering Sciences
          University of Florida
          202 Nuclear Sciences Center
          Gainesville, Florida 32611
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16. MATERIAL AVAILABLE
NESC0486/01
File name File description Records
NESC0486_01.001 SOURCE PROGRAM (F4) 2175
NESC0486_01.002 SAMPLE CASE INPUT DATA 36
NESC0486_01.003 SAMPLE CASE PUNCHED OUTPUT 15
NESC0486_01.004 SAMPLE CASE PRINTED OUTPUT 734
NESC0486/02
File name File description Records
NESC0486_02.001 SOURCE PROGRAM (F4) 2191
NESC0486_02.002 SAMPLE PROBLEM INPUT DATA 36
NESC0486_02.003 JCL 3
NESC0486_02.004 SAMPLE PROBLEM PRINTED OUTPUT 698
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17. CATEGORIES
  • E. Space-Independent Kinetics

Keywords: delayed neutrons, reactivity, reactor kinetics, temperature feedback.